A conventional hot-air clothes dryer operates by drawing air from the room in which it is located, heating the air, circulating the heated air among wet or damp clothes to absorb moisture from the clothes, and then venting the heated, moist air to the outside of the building (typically a dwelling) in which the clothes dryer is located.
Referring now to FIG. 1A, an exemplary prior art hot-air clothes dryer is indicated generally by the reference numeral 10A. The dryer 10A comprises a dryer housing 12A which includes a dryer air inlet 14A and a dryer air outlet 16A. The dryer 10A also includes a heater 18A, a pump 20A (in the illustrated embodiment a fan 22A driven by a motor 24A), and a driven rotating tumbler drum 26A which has drum air inlet apertures 28A located at the rear thereof. In the illustrated embodiment, the motor 24A also drives the tumbler drum 26A by way of a drive belt 30A. The dryer housing 12A also includes a door 32A enabling clothes to be placed inside the tumbler drum 26A through an open front end thereof. The door 32A is hollow and has door air inlet apertures 34A defined in its inner face so that the interior volume of the tumbler drum 26A can communicate with the interior of the door 32A, and a door outlet 36A which communicates through a lint trap 38A with the fan 22A. The fan 22A is positioned downstream of the dryer air inlet 14A, heater 18A, tumbler drum 26A, door 32A and lint trap 38A, and upstream of the dryer air outlet 16A, which communicates with the building exterior through a vent passage 40A formed by tubing that extends through an exterior wall 42A of the building.
In operation of the exemplary dryer 10A, the fan 22A draws air, denoted by the arrows 44, into the dryer housing 12A through the dryer air inlet 14A. The air 44 is drawn past the heater 18A, which heats the air 44, and then through the drum air inlet apertures 28A into the tumbler drum 26A. Inside the tumbler drum 26A, the heated air 44 absorbs moisture from the clothing (not shown) as the tumbler drum 26A rotates, and then the heated, moist air 44 passes through the door air inlet apertures 34A into the hollow interior of the door 32A. The heated, moist air 44 is then drawn through the door outlet 36A and the lint trap 38A, which captures fibers carried by the heated, moist air 44, and then continues past the fan 22A through the vent passage 40A to the exterior of the building.
FIG. 1B shows an exemplary prior art hot-air clothes dryer 12B which is identical to the exemplary prior art dryer 12A except that the dryer air inlet, denoted by reference numeral 14B, is located at a dryer air intake region at the rear of the dryer 12B, rather than at the front as with the exemplary prior art dryer 12A, and comprises a plurality of apertures 15B. As such, identical reference numerals, except with the suffix “B” instead of “A”, are used to denote corresponding features.
With hot-air clothes dryers such as those described above, it is important that the heated, moist air be vented to the outside of the building, otherwise the moisture can result in the development of mould or otherwise damage the building.
As more and more buildings, and particular houses, become well insulated and effectively sealed from the outside environment when the doors and windows are closed, the drawing of air from inside the room can be problematic, since the insulation and sealing impedes the inflow of replacement air into the building.
Proposals have been made for a dryer which draws air from the outside of the building rather than from inside the building. For example, U.S. Patent Application Publications No. 2008/0110044, 2008/0113609 and 2008/0110041 in the name of Gregory Ehlers, each of which is hereby incorporated by reference, teach a dryer which is constructed to draw air from outside of the building in which it is located.
FIG. 2 shows an exemplary hot-air clothes dryer 210 which is designed to draw air from outside of the building in which it is located. The first exemplary dryer 210 is similar to the exemplary prior art clothes dryer 10B, and comprises a dryer housing 212 which includes a dryer air inlet 214 and a dryer air outlet 216. Like the prior art dryer 10B, the first exemplary dryer 210 comprises a heater 218, a pump 220 comprising a fan 222 driven by a motor 224, as well as a driven rotating tumbler drum 226 having drum air inlet apertures 228 located at the rear thereof, with the motor 224 also driving the tumbler drum 226 by way of a drive belt 230. As with the prior art dryer 10B, a hollow door 232 permits access to the tumbler drum 226, and includes door air inlet apertures 234 enabling air 244 inside the interior volume of the tumbler drum 226 to communicate through the interior of the door 232, door outlet 236 and a lint trap 238 with the fan 222. Like the prior art dryer 10B, when installed for use the first exemplary dryer 210 is located inside a building, adjacent a wall 242 thereof.
Unlike the illustrated prior art dryer 10B shown in FIG. 1B, which draws air from inside the room in which it is situated, when installed the exemplary prior art dryer 210 shown in FIG. 2 will draw intake air directly from the exterior of the building in which the dryer 210 is located.
As shown in FIG. 2, the dryer air inlet 214 communicates along an intake air passage 246 defined by a linkage 247 with an inlet aperture 248 disposed outside of the building in which the first exemplary dryer 210 is situated so as to receive air directly from outside the building. Similarly, the dryer air outlet 216 communicates along an output air passage 250 defined by a linkage 251 with an outlet aperture 252 disposed outside of the building to vent the heated moist air to the outside. The intake air passage 246 and the output air passage 250 are arranged concentrically, with a portion of the linkage 251 defining the output air passage 250 disposed within, and surrounded by, a corresponding portion of the linkage 247 defining the intake air passage 246 and supported by spokes 260.
The dryer air inlet 214 is in communication along a heated path with a drying chamber; air entering through the dryer air inlet 214 is drawn past the heater 218 into the tumbler drum 226. The dryer air outlet 216 is in communication with the drying chamber and, via an output air path, with an outlet aperture disposed outside of the building. In the first exemplary dryer 210, air from the tumbler drum 226 is drawn into the door air inlet apertures 234, through the interior of the door 232, door outlet 236 and lint trap 238 to the dryer air outlet 216 and then along the output air passage 250 defined by the linkage 251 to an outlet aperture 252 disposed outside of the building. The pump 220 comprising the motor 224 and fan 222 moves air, denoted by arrows 244, from the inlet aperture 248, along the intake air passage 246 to the dryer air inlet 214, along the heated path, that is, past the heater 218, and through the drying chamber, in this case the tumbler drum 226, to the dryer air outlet 216, and then along the output air passage 250 to the outlet aperture 252.
While dryers which are designed to draw air from outside of the building in which the dryer is located may avoid the problem of drawing air from inside a well-insulated and well-sealed structure, they must replace an existing dryer which may be in perfectly good working order. The cost of such replacement would serve as a significant deterrent to adoption, and even when the cost does not deter replacement, there is waste because the previous dryer will be discarded even if it still has many years of useful life.
In addition, where a dryer that draws intake air directly from the exterior of the building in which the dryer is located includes an intake air passage and output air passage that are concentrically arranged, as with the dryer 210, such dryers cannot be easily adapted to the external lint traps commonly used in multi-unit residential buildings, such as condominiums and apartment buildings. Such lint traps are typically housed in the wall or ceiling of the room in which the dryer is located to remove lint that was not captured by the lint trap in the dryer itself. An example of such a lint trap is taught by U.S. Pat. No. 6,997,966 to Iantorno, the teachings of which are hereby incorporated by reference. FIG. 7A shows a dryer 710 inside a room 702 which has walls 704 and a ceiling 706. The air outlet 716 of the dryer 710 is coupled to an exhaust duct 714 running through the wall 704 and ceiling 706 to an exhaust vent 718. A lint trap 720 of the type taught by U.S. Pat. No. 6,997,966 to Iantorno is also disposed in the wall or ceiling and is interposed between two sections of the exhaust duct 714. Although two lint traps 720 are shown in FIG. 7A for purposes of illustration, with one lint trap 720 in the ceiling 706 and one lint trap 720 in the wall 704, typically a dryer installation will have only one lint trap, located in either the wall or the ceiling. As shown in FIG. 7B, the lint trap 720 comprises a filter enclosure 730 in the form of a rectangular parallelepiped having one open face 732 and a filter door 734 having a filter member 736 mounted diagonally thereon. The filter enclosure 730 has an enclosure inlet 738 and an enclosure outlet 740 which are opposed to one another and can be connected to the sections of the exhaust duct 714, as shown in FIG. 7A. The filter member 736 is slidingly received in the filter enclosure 730 through the open face 732 so that the filter member 736 lies across the airflow path from the enclosure inlet 738 to the enclosure outlet 740, with the side edges 742 of the filter member 736 engaging inner corners of the enclosure 730 and the filter door 734 closing the open face 732 to complete the enclosure 730. The filter door 734 and filter member 736 can be removed for cleaning or replacement of the filter member 736. A dryer that draws intake air directly from the exterior of the building in which the dryer is located and which includes an intake air passage and output air passage that are concentrically arranged cannot easily be used with a conventional lint trap such as that taught by U.S. Pat. No. 6,997,966 to Iantorno, such as the lint trap 720, because the filter member (e.g. filter member 736) would interfere with the flow of air to the dryer from outside the building.